1. Field of the Invention
The present invention concerns a method of making articles by the use of an organic layer developed by a plasma atmosphere for pattern delineation.
2. Description of the Prior Art
In the production of solid-state devices, including, for example, semiconductor devices, magnetic bubble devices, optical waveguide devices, etc., it is necessary to form patterns having very small dimensions on a substrate or other device precursor. In addition, lithographic shadow masks are likewise patterned to define device geometries. Lithographic resists are typically used that are patterned by radiation and developed. The developed pattern may thereafter be transferred to an underlying layer by a variety of techniques, including plasma etching, ion milling, ion implantation, wet chemistry, etc. The patterning radiation has included a variety of types, including electron beams, ultraviolet light, and visible light. Other sources are also being explored, including X-ray radiation and ion beams. In the past, the development of the irradiated resist has frequently been by dissolution of the irradiated or unirradiated regions of the resist by means of a development solution. This produced either a positive tone image or a negative tone image, respectively, depending upon the resist chemistry and developer type. Recently, a trend has occurred away from liquid developers, especially in very fine line lithography. Dry development has been accomplished by exposure of the resist to a plasma; see, for example, U.S. Pat. No. 4,232,110, coassigned with the present invention.
It has been found by one of the present inventors that by including an organometallic monomer in a polymeric resist, protective regions can be formed in irradiated regions of a resist upon plasma etching. For example, protective oxide regions can be formed in an oxygen plasma that etches the unprotected regions; see U.S. Pat. No. 4,396,704, coassigned with the present invention. Both silicon and nonsilicon organometallic monomers have been found useful. Another recent lithography technique has been developed by two of the present inventors, whereby ions, for example metallic ions, are selectively implanted in a material. The implanted ions react with a plasma, typically oxygen, to form a compound that protects the implanted region upon subsequent plasma etching; see U.S. Pat. No. 4,377,437, coassigned with the present invention.
Not only must a resist technology provide for the generation of fine lines, but in many cases it must also accommodate step coverage over previously formed features on a device precursor, while still maintaining the geometry of the pattern as it is transferred from the resist into the device precursor. Maintaining fine lines usually requires relatively thin resists, whereas providing good step coverage usually requires relatively thick resists. To accommodate these conflicting requirements, multilevel resists have been invented. In the multilevel technique, a relatively thick resist is initially applied to a device precursor to provide for good step coverage and provide a relatively planar surface, with a thin resist being deposited thereon. A pattern is then generated in the thin resist and transferred to the underlying layer by reactive ion etching or other techniques. It is also frequently advantageous to interpose a hard metallic or oxide layer between the two resist levels; see, for example, U.S. Pat. No. 4,244,799, coassigned with the present invention. For a recent review of multilevel resist technology, see "Multilayer Resist Systems and Processing," B. J. Lin, Solid-State Technology, pages 105-112, May 1983.